Means for producing electric impulses



June 6, 1944. P. MORLAND El'AL.

MEANS FOR PRODUCING ELECTRIC IMPULSES Filed Sept. 3, 1941 IIVIENTORPans/v Menu/yo Jones/v A001. SM/TH Patented June 6, 1944 l MEANS FORPRODUCING ELECTRIC IMPULSES Preben Morland, Gentofte, and Jorgen AdolphSmith, Copenhagen, Denmark; vested in the Alien Property CustodianApplication September 3, 1941, Serial No. 409,384 In Denmark June 21,1940 7 Claims.

The invention relates to an apparatus for treatment of nerves andmuscles by means of electric impulses, especially for artificialinnervation of 'muscles, for instance for therapeutic purposes. Theapparatus according to the invention is especially adapted for use inthe training of muscles.

For the above mentioned purpose, electric impulses are used the voltagecurve of which may be monopolar, i. e. the voltage curve for eachindividual impulse is either entirely above or entirely below a voltageof repose which generally will be zero. Usually, however, the voltagecurve will be dipolar, i. e. the voltage curve has one portionsituatedon one side of the voltage of repose, and an adjoining portion situatedon the opposite side thereof. In therapeutics, such impulses arefrequently called monophase and diphase or else galvanic and faradicimpulses, respectively. The duration of each impulse will generally beconstant and is referred to, in the following, as the impulse duration.The individual impulses are emitted in succession, in such a manner thatthe time interval between two successive impulses is always larger thanthe duration of each individual impulse.

Further, the time interval between the impulses as well as theiramplitude should be able to be varied continuously and automatically.Apparatuses by which such electric impulses may be produced are known,but the possibilities of variation offered by these apparatuses are verylimited, and the variations are effected by deficient mechanical means.

The present invention has for its object to provide an apparatus bywhich it is feasible to perform at any time the desired variations inthe ranges of variation for the amplitude and time interval of theimpulses, and in the manner in which the amplitude and time interval ofthe impulses are varying.

According to the invention, this result is attained in that theapparatus is fitted with means for producing a rhythmically pulsatingcurrent which is utilized for controlling the time interval Theapparatus may have two potentiometers through which the rhythmicallypulsating current is passing, and from which the controlling voltagesare taken that serve to control the time interval and the amplitude ofthe impulses.

The said rhythmically pulsating currents may be produced in the anodecircuit of a discharging valve, by means of a relay the coil of which isinserted in the anode circuit of thevalve, and which alternately chargesand discharges a condenser inserted in the control circuit of the valve.

The anode circuit of the valve may contain potentiometers from which thevoltages for controlling the time interval and the amplitude of theimpulses are taken. In order to be able to reduce arbitrarily to zerothe minimum value of the current through the potentiometers, without therelay being prevented from operating, a portion of the circuitcontaining the relay coil, the valve and the potentiometers may beshunted with a variable resistance.

In order to change the shape of the pulsating current, means may befound for altering the charging current and the discharging current "ofthe condenser independently of each other.

The impulses may be produced by means of a condenser, by charging ordischarging the same by way of a discharging bulb of the kind havingbetween the individual impulses and similarly ably formed by chargingand discharging currents for a condenser or, maybe, by an amplificationof such currents.

an igniting voltage that is higher than the extinguishing voltage, andby charging or discharging the condenser by way of a discharging valvethe grid voltage of which is controlled by the rhythmically pulsatingcurrent, the time interval between the impulses being thus altered inaccordance with the said current. The minimum time interval between theimpulses may be modified by altering a grid bias imposed on the valve. 7

The discharging bulb may preferably be a glow lamp.

The adjustment of the amplitude of the impulses may be effected by anamplifier valve in which the impulses are amplified, and on the gridvoltage of which the rhythmically pulsating current is superimposed, insuch a manner that the impulse amplitude varies in accordance with thevention,

Fig. 2 the voltage curves for a series of 'impulses produced by means ofthe apparatus shown in Fig. 1, and

Fig. 3 the voltage curves for two individual impulses.

The apparatus shown in Fig. 1 consists of three parts, viz. one part forproducing the rhythmically pulsating current, one part for producing theimpulses and for controlling the mutual time interval between thelatter, and one portion for controlling the amplitude of the impulses.

The rhythmically pulsating current is .produced by means of a triodevalve I the anode 2 of which is connected, by way of a relay coil 3v fora relay 4, to the positive terminal 5 of a source of voltage. Thecathode I in the valve I is connected to the negative terminal 6 of thesource of voltage by way of two parallel current paths, viz. partly byway of a potentiometer B with a sliding contact 9, and partly by way ofa series connection consisting of a resistance I6 and a potentiometer IIwith a sliding contact I2. The two current'paths may be alike, and aremerely shown different in order to indicate that each currentpath mayeither consist merely of a potentiometer or of a potentiometer connectedin series with a fixed resistance. The two potentiometers'may further bereplaced by one single potentiometer having two sliding contacts adaptedto be adjusted independently of each other. Across a resistance I4 thearmature of the relay 4 is connected to the grid I3 of the valve I,which grid is further connected to the cathode I by way of'a resistanceI5 and a condenser I6. A battery I'I, the positive and negativeterminals of which are marked 18 and I9 respectively, has two cutlets2i] andZI, the voltage being more positive at the outlet 20 than at theoutlet 2|. he'outlet 26 is connected to the cathode I. The positiveterminal I6 of the battery is connected, by way of a potentiometer 22with a sliding contact 23 and, by way of a resistance '24, to theoutlet'ZI which by way of a resistance 25 and a potentiometer 26 with asliding contact 21 is connected to; the negativeterminal I9 of thebattery. The sliding contacts 23 and 21 are con.- nected; respectively,to a circuit-breaking contact 28 and a. circuit-closing contact 29intherelay 4.

When the" current in the relay coil .3 alternately'assumes variousvalues, the armature I3 will alternately'close a contact with thecontacts 28" and :29; At the moment-when a contact is closed forinstance betweenthe armature I3 and the contact-28, the current in therelay coil will be relatively small. Across the potentiometer 22, thesliding :contact 2.3, the contact 2 8 and the re-' sistance Id-the gridI3 will receive a voltage that is-higher than the voltage impartedsubsequently thereto by way of the potentiometer 26, the sliding contact21 and the contact 29, when the armaturelfi' is attracted. The grid I3,however, does not at once receive the voltage possessed by the slidingcontact 23, as the condenser I6 must first be charged by way of theresistances I4 and I 5 which'limit the current. Gradually, as the hasdropped to a certain value, th armature I3 recedes, and closes again acontact with the contact 28 causing the condenser I6 to be charged againwith a positive voltage on the grid side. By the chargings anddischargings of the condenser I6 produced in this manner, a rhythmicallypulsating current is produced in the anode circuit of the valve I, andcorresponding voltages will occur on the potentiometers 8 and I I. Theform of these voltages may be varied by varying the magnitude of one ormore of the coupling elements in the circuit having connection'to thegrid I3. When these values have been fixed, the time required by thevoltage for rising and for dropping may be varied, independently of eachother, by means of the sliding contacts 23 and 2?. If for instance thesliding contact 23 is approached to the Positive end of thepotentiometer 22, the voltage difference between the cathode I and thesliding contact 23 will increase. The condenser I5 will consequently becharged more quickly, and the anode current of the valve will increasemore quickly.

By the arrangement described heretofore the current through thepotentiometers 8 and I I does not vary down to the minimum limit zero.In order to attain this result, there is provided, between the anode 2and the negative terminal 6 of the source of voltage, a variableresistance 36 serving to shunt the series connection of the valve 1 andthe potentiometers 8 and I I inserted in parallel. The resistance 30 isadjusted in such a manner that the current through the valve I and thepotentiometers 8 and II will approach zero as closely as desired, whenthe current in the relay coil 3 has dropped to its minimum value atwhich the relay armature I3 recedes. The varying current through therelay coil 3 will not be altered in consequence hereof.

Every point of the potentiometer 22 has a voltage that is higher thanthe voltage required in order that the current passing through the relaycoil 3 may be sufficiently intense to cause the coil to attract thearmature I3, and every point of the potentiometer 25 has a voltage thatis lower than the voltage required in order that the current through therelay coil 3 may be so small that the armature I3 recedes.

The portion of the apparatus in which the impulses controlled by therhythmically pulsating current are produced, and in which the mutualtime interval of the impulses is adjusted, contains a pentode Valve 3|the controlling grid 32 of which is connected, by way of a filter chainconsisting of two resistances 3,3 and 34 and a condenser 35, to thesliding contact I2 on the potentiometer II. The valve 3| has further ananode 36, an intercepting grid 31, a shielding grid 38 and a cathode 39.The intercepting gri 31 is connected to the cathode 39. The shieldinggrid 38 receives a positive voltage by way of a sliding contact 40 on apotentiometer -4I inserted between the terminals 5 and 6 of the sourceof voltage. A condenser 42 isprovided between the shielding grid 38 andthe negative terminal 6. By way of a glow lamp 43, the anode 36 isconnected to the positive terminal 5 and, by way of a condenser 44, tothe negative terminal 6. The cathode 39 is connected to a slidingcontact45 on a potentiometer 46 which is inserted in a resistance chaincontaining further the resistances 41 and 48, and being connected by wayof the terminals 5 and :6 of the source of voltage, The cathode 39 iscoupled to the negative terminal 6 by means of a condenser 49. I

The'valve 3| acts as a variable resistance disposed as a shunt acrossthe condenser 44. When the condenser is charged by way of th glow lamp43, the latter is extinguished, and the condenser 44 is discharged byway of the valve 3|, until the voltage over the condenser has become solow that the glow lamp 43 is ignited again, and charges the condenser 44etc. An impulse is produced at each charging and subsequent dischargingof the condenser 44.

The voltage impulses occurring by way of the condenser 44 have aduration that is mainly equal to the time interval between theindividual impulses. The voltage rises quickly and in a rectilinearmanner to a certain value, and drops then relatively-slowly to a certainlower value, after which it rises quickly again etc. The Voltage curvefor the condenser 44 assumes consequently a toothed appearance, eachtooth corresponding to one single impulse. The shape of the impulses,however, is. changed during their further passage through the apparatus,as further described in the following.

. The time interval between the impulses may be modified by altering theresistance in the valve 3|. This resistance is depending on the voltageof the grid 32 in comparison with the cathode 39. If the grid voltagerises, the resistance in the valve 3| is reduced and, consequently, thetime interval between the impulses becomes'shorter. The grid voltageand, consequently, the time in terval between the impulses arecontrolled by the voltage of the sliding contact 12 relatively to thecathode 39, and this voltage is determined partly by the rhythmicallypulsating current passin through the potentiometer II and partly by thedrop of voltage across the resistance that is inserted between thesliding contact 45 and the negative terminal 6 of the source of voltage.This drop of voltage may be regulated by means of the sliding contact45, the position of which determines the maximum time interval betweenthe impulses. By means of the sliding contact l2, the range ofvariations for the time interval is adjusted. Gradually as the slidingcontact I 2 is approached to the negative end of the potentiometer II,the range of variations for the time. interval becomes smaller andsmaller, and finally a constant time interval between the impulses isreached which is determined by the position of the sliding contact 45.

When the maximum time interval for the impulses is altered, the minimumtime interval will be altered at the same time. provided that the rangeof variations remains the same. In order impulses may be reduced,independently of the grid bias for the valve 3|.

The'voltage variations produced on the condenser 44 are directed, by wayof a coupling condenser 50, to'the last part of the apparatus in whichthe amplitude of the impulses is controlled. This part contains anamplifier valve Si in the shape of a pentode with a cathode 52, acontrolling grid 53, a shielding grid 54, an intercepting grid 55 and ananode 56. The impulses are directed from the coupling condenser to thecontrolling grid 53. The anode 56receives a positive voltage by way of achoking coil 51. The intercepting grid is connected to the cathode 52.The shielding grid 54 receives positive voltage by way of a resistance58, and is coupled to the negative terminal 6 of the source of voltage,by means of a condenser 59. The cathode 52 is connected to the negativeterminal '6 by Way ofa variable resistance 60 which is shunted with acondenser 6|. 7 r

The voltage taken from the potentiometer 8 by means of the slidingcontact 9 .is directed to the grid 53 by Way of a filter chainconsisting of two resistances 62 and 63 and a condenser 64, in such amanner that the constant grid bias determined by the magnitude of thevariable resistance 60 is superimposed with the voltage determined bythe rhythmically pulsating current passing through the potentiometer,

by way of thelower part of the potentiometer to be able to alter themaximum time interval. Y

without altering the minimum time interval. the range of variations forthe time interval must be altered correspondingly. This may be done forinstance by inserting, between the sliding contact l2 and the negativeterminal of the source of voltage, a variable resistance which s dimensioned in such a manner, and the controlling sh aft of which is coupledmechanically to the con olling shaft of the potentiometer 46 in such .amanner that a change in the maximum time intervalwill not influence theminimum time nterval, but will solely influence the range of variations.Such a variable resistance is not shown on the drawing. a

The maximum time interval is further dependent on the position of thesliding contact an on the potentiometer 4|. in such a manner that byapproaching this contact to the positive end of the potentiometer thetime interval between the 8 determined by the positionof the slidingcontact 9. The amplification produced in the valve 5| is varied in timewith the rhythmically pulsating current. Th amplified impulsesaredelivered from a terminal 65 which is connected to the anode 56 byway oia condenser 66, and a terminal 6'! which is connected to thenegative terminal 6 of the source of voltage. The range of amplificationvariations for the impulses may be adjusted by means of the slidingcontact 9 on the potentiometer 8, and is varied from zero andupward,'while theminimum amplitude may be adjusted by means of thevariable resistance 60. i Y

The magnitude of the impulses directed on to the grid- 53 may be limitedby means of a variable resistance 68; one end of which is -connected tothe grid 53, and the other end of which is'connected to the negativeterminal 6, by way of a condenser 69. When theresistance 68 is reduced,the impulses will be reduced.

As'mentioned above, the shape of each individual impulse is alteredduring the. passage through theapparatus. The curve of voltage for thevoltages "occurring on the condenser 44 has a toothed appearance, eachtoothcorresponding to one single impulse. When the im-, pulses havepassed the condenser 50, which for instance may be about cm., theirvoltage curve has about the shape of a triangle with a relatively shortbase, and the duration of the impulses is consequently smaller than thetime interval between. two successive impulses. I In consequence of theimpedances contained in the o tlet circuit of the valve 5|. the impulsesbecome dipolar; and assume the shape-shown in the voltage on the outletterminals or the apparatus being plotted as a function of the time. Thefinely drawn lines H and 12 through the voltage maxima and minima,respectively, of the individual impulses do not indicate the voltagesoccurring at the outlet terminals of the apparatus, but are merelyenveloping curves for the series of impulses, and they illustrate therhythmically pulsating variation of the impulse amplitude. The portionof the enveloping curves for which the impulse amplitude is increasingand decreasing are called, respectively, the wave rise and the wavedrop. By the selection of various amplifier valves, and by a suitablese- 7 lection of the coupling elements contained in the inlet circuit ofthe valv I, and by the'intro-.

duction of capacities, resistances and self inductions in the gridcircuit for the Valve 5|, the shape of the wave rise and the wave dropmay be adjusted as desired. Analogously, the modification of the timeinterval between successive impulses at various points of the envelopingcurves may be adjusted as desired. The difference in height between themaxima and minima of the enveloping curves indicates the range ofamplitude variation, and the minima of the en- Veloping curves indicatethe minimum amplitude. The corresponding time interval between theimpulses is the maximum time interval which may be adjusted to anydesired value by means of the sliding contact 40, and may be alteredinside of any desired range by means of the sliding contact 45. Theminimum time interval occurs in the maxima of the enveloping curves, andthe difference between the latter and the maximum time interval is thevariation range which may be modified by the sliding contact l2, and hasthe lower limit zero, independently of the maximum time interval.

The time passing between two wave summits of the enveloping curve may bevaried by means of the sliding contacts 23 and 21. A change in thisrange of variations may be effected by altering the magnitudes of thecoupling elements entering in the grid circuit for the valve l,or by theaddition of further coupling elements. The charging of the condenser l6may also'be effected by means of one valve more instead of the batteryshown, or by means of a mechanically driven sliding contact which altersthe voltage of the grid l3.

.Instead of the triode valve I, there maybe used a valve with moregrids, any one of which maybe used as a controlling grid. Acombinationgrid may also be used having such a num ber of electrodesthat/both the productionof the rhythmically pulsating current and theamplitude variation or the variation of the time interval between theindividual impulses may be effected in the same valve.

The coupling between the valves 3| and 5! may be altered in such amanner that the impulses are directed from both sides of the glow lamp43 to cathode 52 and the grid 53, respectively, by means of suitablecoupling elements.

,The bulb 43 may be a glow lamp or other known discharging valve, theignition voltage of which is higher than the extinguishing voltage, forinstance a 'so-called gas diode. In order togain stability, thecondenser M is coupled to the negative terminal 6 of the source ofvoltage, but it may also be disposed in parallel to the discharging bulb43. When a glow lamp is used, the individual impulses occur with theshape shown in Fig.

tus. The figure shows the voltage variation for two successive impulsesl3 and 14. The oscillations are dipolar, and the two halves of eachimpulse variation may be rendered more or less symmetrical by theinsertion of impedances in the circuits in which the glow lamp isinserted. The duration and the time interval of the impulses are marked1? and T, respectively.

The amplifier valve 5| and its coupling may be varied, the impulses,however, being constantly delivered to one of the grids of amplifiervalve. The ratios between the shown combinations of fixed resistancesand potentiometers should preferably be selected in such a manner thatthe desired variation will be attained by a full rotation of thecontrolling shafts of the potentiometers.

The time interval T between the impulses varies mainly between 10seconds and 450 of a second. The amplitude varies between zero and about20 volts.

Having thus described my invention, what I claim is: u

1. An apparatus for the treatment of nerves and muscles by means ofelectric impulses, comprising means for producing a succession ofelectric impulses, a device for generating a rhythmically pulsatingcurrent, means controlled by said pulsating current to vary the timeintervals between said individual impulses, and independent lyadjustable means also controlled by said pulsating current to vary theamplitude of said impulses.

2. An apparatus, as claimed in claim 1, in which said device forgenerating the rhythmically pulsating current includes a condenser whichis alternately charged and discharged. i

3. An apparatus, as claimed in claim 1, in which said means forvaryingthe time intervals between the individual impulses and said means forvarying the amplitude of said impulses, each includes a separatepotentiometer by way of which the rhythmically pulsating current ispassing and from which the controlling voltages for varying the timeinterval and amplitude, respectively, of the impulses are delivered.

7 4. An apparatus, as claimed in claim 1, in which said device forgenerating the rhythmically pulsating current includes a dischargevalve,v a relay having its coil inserted in thejanojde circuit of thedischarge valve, and a condenserv inserted in the inlet circuit of saidvalve and being controlled by said relay to be alternatelycharged anddischarged in order to produce, variations,in the anode current of thevalve.

5. An apparatus, as claimed in claim 1, in which said device forgenerating the rhythmically pulsating current includes a dischargevalve,a relay having its coil inserted in the anode circuit of a saiddischarge valve, anda condenser inserted 3, at the outlet terminals ofthe appara- 7 into the] inlet circuit of said discharge .valve and beingcontrolled by said relay to be alternately charged and dischargedinorder to produce variations in the anode current of the valve, saidmeans for varying the time intervals between the individual impulsesand'said means for varying the amplitude of said impulses, eachincluding 'a separate potentiometer inserted in the anode circuit ofsaid valve, said apparatus including further a variable resistanceshunting a portion of said device for generating the rhythmicallypulsating current includes a condenser which is alternately charged anddischarged and means for altering the charging current and thedischarging currents of the condenser, independently of are amplified,means to superimpose the rhythmically pulsating current on the gridvoltage of said amplifier valve in order to vary the amplitude of theimpulses, and means for altering a grid bias imposed on the valve inorder to vary the each other, and consequently the shape of the 6minimum voltage of the impulses.

rhythmically pulsating current.

7. An apparatus, as claimed in claim ,1, comprising an amplifier valvein which the impulses PREBEN MORLAND. JORGEN ADOLPH SMITH.

